Multiple-dome dam



April 9, 1929. c; OLB ERGV 7 1,708,452

MULTIPLE DOME DAM Filed 001:. 20, 1925 3 Sheets-Sheet 1 t wanton April 9, 1929. c QLBERG 1,708,452

MULTIPLE DOME DAM 25 Sheets-Sheet 2 Filed 001:. 20, 1925 April 9, 1929. c; QLBERG 1,708,452

MULTIPLE DOME DAM Filed Oct. 20, 1925 5 Sheets-Sheet 3 Patented Apr. 9, 1929.

UNITED STATES CHARLES R. OLBERG, OF LOS ANGELES, CALIFORNIA.

MULTIPLE-DOME DAM.

Application filed Gctober 20, 1925. Serial No. 63,735.

This invention relates to masonry dams, and has for its principal object the provision of a dam in which the volume of the dam is reduced to a minimum while at the same time obtaining the maximum efficiency and strength of the material of which the dam is constructed.

A further object of the present invention is the provision of a masonry dam suitable for use in a canyon in which the dam consists of a plurality of dome-shaped walls supported on either side by the canyon wall and supported centrally by piers in which the greatest possible strength is secured with a minimum quantity of material and at a rel atively low cost of construction.

A further and important object of the pres ent invention is the provision of a multiple dome dam in which the water pressure is transmitted to the piers by dome act-ion transmitting the pressure of the water in all directions, the walls of the domes being. so shaped that the pressure and stresses due to change in temperature and to the shrinkage of the material are distributed throughout the material so as to obviate either compressive or tensile stresses beyond safe limits.

Still further objects of the present'invention are the provision of a multiple dome dam in which there is no tension in the dome or in the piers except in the roadway section of the dome which is the only part of the structure requiring reinforcing under load, the dam having no cantilever action in the walls of the dome; and the provision of a method whereby the spans of the walls supporting the Water pressure vary inversely as the water pressure making it possible to have a thickness of dome walls such that the temperature and shrinkage forces at full load do not produce stresses which would'cause the masonry to crack or which would make it necessaryto use reinforcing steel in the domes. It is necessary however, to use a small quantity of steel reinforcement to take care of the greatest tension stress which occurs when the dam is empty and subject to maximum temperature conditions.

In the gravity type of dam, sheer weight is employed to prevent overturmng from water pressure. This is very uneconomical in the use of material and produces an uneven pressure on the base. My improved dam makes use of the strength of the material which makes for a minimum quantity and a minimum cost. In arch and multiplearch dams heretofore constructed, the pres sure of the water is transmitted to the piers and canyon walls by arch action only. In my improved dome dam the water pressure is transmitted to the piers and canyon walls by dome action which transmits the pressure of the water in all directions.

In arch and multiple arch dams heretofore construct-ed there is cantilever action upon the arch walls which produces tension stresses on the upstream side of the arch wall. These tension forces are usually sogreat that horizontal cracks occur on the upstream side of the arch wall at various elevations from the bottom to at least half way to the top. This is obviated in the present invention by shaping the walls of the dam so that the cantilever action which produces the cracks will be eliminated from the dome walls. This is accomplished by making the wall supporting the water pressure dome-shaped and then the forces which tend toward cantilever action are transmitted directly into the base and piers which support the dome-shaped walls. The intersection of the dome-shaped walls by any plane forms an arch so that the improved type of dome dam gives arch action in all directions.

Heretofore in arch dams of the multiple arch type, the span of the arches has been equal or very nearly equal from the top to the bottom. Inasmuch as the pressure of the water increases with the depth, the span of the arches or .walls supporting the pressure should decrease with the increase of pressure. IVhen the span of the wall supporting the water pressure is constant, the thickness of the wallmustbemade much greater, and when considering the temperature and shrinkage forces, the unit stresses in the material are such that a large quantity of steel reinforcement is required in order to prevent cracks in the arch walls. In my improved type of dome dam the span of the dome decreases as the water pressure increases, which makes it possible to have a thickness of the dome walls such that the temperature and shrinkage forces do not produce stresses which would cause the masonry to crack or require large quantities of reinforcing steel.

In the drawings Figure 1 is a plan view of a dam constructed in accordance with my invention.

Figure 2 is a down stream elevation thereof.

Figure 3 is a vertical section on line of Figure 2.

' stream elevation.

i well known construction.

Figure 5 is a plan of that part of the dam at the bottom of the canyon which smoothes out the base for proper fitting of the domes.

Figure 6 is an upstream elevation of the structure shown in Figure 5.

Figure 7 is a vertical section thru line7-7 ofFigure 6.

Figure 8 is a section on line 8'8'of Figure'3.

In. the drawings the'dam is represented as a structure built between the steepwalls of a canyon and while a dam built in substantial accordance with that shown in the figures is the preferred type, the invention must not be considered as so limited, the particular illustration having been selected because it gives a much clearer idea of the principles of the in vention, and the invention contemplating great ranges of style, including combinations of domes of from identical to widely divergent sizes and cross-sections.

As illustrated, A represents the approximate ground line, B one of the three domes which are here shown as of exactly the same shape,C each of the two piers, D the bridge, E the abutment of the dome shaped walls on the sideof the canyon, F that portion of the piers supporting the roadway section of thedome and the roadway between the domes, and H the foundation rock at the bottom of the canyon. I I

Described very briefly, the dam illustrated is of concrete and consists of three domes of identical size, shape and cross section which may be likened very roughly to sections of an egg shell with the major'a-Xis of the egg at an angle of just roughly i5 to the horizontal with' the butt end of'the egg up and pointing downstream. The two outside domes abut the sides of the canyon at E while between the central dome B and each of the two side domes B there are buttress piers C, quite narrow at the level of the widest part of the domes and gradually increasing in width down to the foundation rock. The roadway'is wide and is supported laterally by the piers C which have integral portions F supporting such roadway sections. The two spillways at either side of the domes are of general and Referring now particularly to Figures-3 and 8 showing cross sections thru the dome, it will be noted that the outside surface of the dome is a section of an ellipsoid which is formed by taking a combinationof parts of spherical surfaces which are tangent at the line of contact;

Figure 8. The'upstream side of this arch is a circular curve and the intrados or downstream side is a three centered curve so se-" The section of the dome looted that thearch gradually decreases in thickness from the abutment to the crown of the arch. The increase in thickness is on the intrados of the arch near the abutments where the pressures are greatest. The numeral 10 indicates the upstream side of the arch, the numeral 11 the downstream side, the numeral 12 the abutment, while numeral 14L- indicates the crown of the arch.

Referring now more particularly to Figure 3 which is a transverse section thru-one of the domes. The dome increases in thickess steadily from its crest or at the roadway section .14, to the bottom. he line 1516 is the axis of generation of the upstream face of the dome, the cross section as seen in Figure 3, being'struck on an arc from'l'i to 18 with a center 19, at the crest from 18 to the roadway at 1st from the center 20, and the bottom 'portion'of the are from 17 to the foundation rock H being struck from the center 21. Y

The intrados cross section are is struck from approximately at l'Tto approximately at 18 from a center 24 located further from the axis 15- -16 and giving a constantly in creasing thicknessto the section illustrated in the figure. The are of the upper or crest portion'of the intrados may be substantially parallel to the are from '18 to the roadway while the lower section from opposite 17 to the foundation rock is struck on a short radius from the center'26, this section being the approximation of the point of the egg, the simile as vill be noted, being a rough approximation only, since the ellipsoid is much elongated in comparison'with the true egg shape. 'The plan of-thepier foundationis indicated by the area 27, 28, 29, 30, 31, 32. 33, 34-, 27 this being the greatest crosssection of the pier. The thickness and the length of the piers are made to vary with the vertical and the horizontal pressures on it dueto the combined water pressure and the weight of the dam walls, these forces being naturally greater at the bottom: The piers arethirinest at 35-36 c'orrespondin in elevation to the lin'e37-35 where the span of the dome is greatest. The thickn .ssof the pier where it is'enlarged to fit the damfor the roadway section is indicate-dat F. 38 indicatesthe springline of the intrados of the dome and ferred to the canyon bottom, the piers, and

the canyon walls bydome action. The pressure at the bottom due to the vdome action thru the section shown in Figure Flis transferred to the bottom thru the line 40%1 while the component of the weightof the dome is transferred to the bottom thru the. line 4042. r

II of the dome, indicates the lowest part of the intrados of the dome and i6 indicates the farthest upstream part of the dome. In igures 5 and '7 the numerals a7 and 4-8, re- :p ctively, indicate the upstream and downtream margins of the dome.

The stresses in the vertical element of the dam are transmitted in the part to the founoation rock H and in part to the roadway D which is supported laterally by the piers C. All forces which are transmitted from.

the dome shaped walls upon the roadway are transmitted to the piersC and thru these to the foundation rock H.

While the unit cost of the concrete for domes will average from one-lifth to onefourth more than with avariable radius dam due to the 152% min preferred, the total number of cubic yards required. for the variable radius'dam will be from one-third to one-half more than for a multiple dome dam,

hence the saving by use of the latter is quite in spite of the fact that apparent, running approximately one-fourth the total cost for the concrete, not counting the saving by reduction of the quantity of steel required.

The saving in cost of a multiple dome dam over a gravity dam is naturally still greater the unit cost of the concrete in the gravity dam is lower than the unit cost-of the concrete of the variable radius dam or of the piers in a multiple dome dam which are of a 1 2 5 mix, the cost of a multiple dome dam being roughly but a half of the cost of a gravity dam due to the latter requiring approximately two and a half times as much concrete.

What 1 claim is 1. A dam made up of a series of domes in which the upstream face of each dome is a surface of generation.

2. A dam made up of a series of domes, each dome being a section of an ellipsoid.

3. A dam made up of a series of domes,

in which each dome is a section of an ellipsoid,

the walls of the ellipsoid increasing in thicknessfrom the crest to the bottom.

a. A dammade up of a series of domes in which the central portion of the upstream and the downstream faces of each dome is asurt'ace of generation, each generatrix be ing a curve of three tangent arcs.

5. A dam made up of a series of domes in which tire central portion of the upstream an d downstream faces of each dome is a surface of generation, each geueratrix being a smooth curve, the radial distance between the generatrices and consequently between said surfaces increasing constantly fromthe crest to the base.

6. A dam made up of a series of domes in which the upstream and downstream faces are each approximately a surface of generation, each generatrix being a smooth curve and the axis of generation being at an acute angle to both horizontal and vertical.

7. A dam of claim 6 in which the axis of generation is at an angle of 45 to horizontal and vertical.

8. A dam made up of a series of domes in which each dome has its tip-stream face a surface of generation and in which the thickness of the wall of the dome increases from crest to bottom and also from crown to abutment.

9. A dam comprising a dome in which the span of the horizontal arch of the dome decreases proportionally to the increased depth of water.

10. A dam consisting of a dome and a pier, in which the span of the horizontal arch of the dome decreases and the horizontal width of the pier increases proportionally to the increase depth of water.

11. A masonry dam comprising a dome, the upstream face of said dome being shaped like part of the surface of an egg, the crest portion being a section of a sphere.

12. The dam of claim 11 in which the major axis of the egg is tilted to present the point of the egg downward and upstream.

13. A masonry dambetwe'en two canyon walls comprising a plurality of dome shaped walls supporting the water pressure, and a plurality of buttress piers, the number of piers being one less than the number of said dome shaped walls.

14. A masonry dam comprising walls of dome shaped contour, in which all inclined planes perpendicular to the spring line of the dome intersecting the upstream face in curves of substantially circular shape, said circular curves diminishing in ratio of rise to span from the bottom upward.

15. A concrete or masonry dam of curved contour resembling a portion of a dome supporting the water pressure, said dome increasing in horizontal span from the bottom upward to near the mid elevation and then decreasing in span toward the top.

16. A masonry dam comprising buttresses and dome shaped walls, the intersection with the dome of an inclined plane perpendicular to the spring line of the dome being essentially a circular arch which increases in thickness from the crown to the spring line.

17. A masonry dam comprising aplurality of domes and piers, the upper portion of the domes and piers jointly forming a bridge.

18. A masonry dam consisting of dome shaped walls supported by piers, said piers decreasing in thickness from the bottom up to about the two-thirds height and thenincreasing in thickness to support the narrower span of the dome near the top. V

19. A masonry dam for a canyon, composed of combined buttress piers and dome shaped Walls, said dome shaped .WEIllS' being supported around their periphery by the canyon Walls canyon bed and said buttress pier 20. A masonry dam comprising flared buttress piers and dome shaped Walls, said flares forming the supports for said dome shaped Walls; i

21. A dome dam having horizontal and vertically curved upstream and down stream faces and having an extended footing to support the bottom and sides of the dome and to eliminate cantilever-action in the dome.

22. A masonry dam comprising a footing a plurality of buttress piers and a dome CHARLES ROLBERG. 

